CODEWITHSUNDEEP
objective-ciosnsstringchar
DrHogie
DrHogie

Reputation: 75

Proper way to convert char* to NSString without initWithCString?

I'm pulling a listing of results from a SQLite3 database into a UITableView. The code where I pull text from the database is like so:

char *menuNameChars = (char *) sqlite3_column_text(statement, 1);
NSString *menuName = [[NSString alloc] initWithUTF8String:menuNameChars];
NSLog(@"Retrieved %s,%@ from DB.", menuNameChars, menuName);

When I use initWithUTF8String, sometimes the information is copied properly from the database. Sometimes though, the information is displayed properly from the char*, but not from the NSString:

2011-10-24 22:26:54.325 [23974:207] Retrieved Cravin Chicken Sandwich – Crispy, (null) from DB.
2011-10-24 22:26:54.327 [23974:207] Retrieved Cravin Chicken Sandwich – Roast, (null) from DB.
2011-10-24 22:26:54.331 [23974:207] Retrieved Jr Chicken Sandwich, Jr Chicken Sandwich from DB.
2011-10-24 22:26:54.337 [23974:207] Retrieved Prime-Cut Chicken Tenders - 3 Piece, Prime-Cut Chicken Tenders - 3 Piece from DB.

Now, if I replace initWithUTF8String with initWithCString, the code works perfectly. However, XCode 4.2 tells me that initWithCString has been deprecated. I know enough to understand I don't want to use deprecated code, but if initWithUTF8String isn't working, what should I use?

Upvotes: 6

Views: 8600

Answers (4)

rob mayoff
rob mayoff

Reputation: 386038

I can see that the dash in your first log line (Retrieved Cravin Chicken Sandwich ...) isn't a simple ASCII HYPHEN-MINUS (U+002D, UTF-8 2D). It's a Unicode EN DASH character (U+2013, UTF-8 E2 80 93). Same for the second line. My guess is they're encoded incorrectly in your database. If you give -[NSString initWithUTF8String:] a C-string that's not valid UTF-8, it returns nil.

Try printing a hex dump of menuNameChars. You can do that by setting a breakpoint on the line after the call to sqlite3_column_text. When the breakpoint is reached, right-click/control-click menuNameChars in your stack frame window and choose View memory of "*menuNameChars" (note the *).

Upvotes: 4

Anthony
Anthony

Reputation: 127

If you look closely at Apple Developer it seems that instance method initWithCString: is only deprecated for the version without explicit encoding: specifier. With good reason one could argue and thus perfectly valid for const char * C-string conversion to NSString. Please compare:

https://developer.apple.com/documentation/foundation/nsstring/1497394-initwithcstring

to newer initWithCString:encoding:

https://developer.apple.com/documentation/foundation/nsstring/1411950-initwithcstring?language=objc

This Foundation API change was made since macOS 10.4+.

Upvotes: 0

ingconti
ingconti

Reputation: 11666

try the power of stringWithFormat:

Upvotes: 2

Chuck
Chuck

Reputation: 237110

It would appear the data is not encoded as UTF-8. You should find out what encoding is being used and then use initWithCString:encoding: and pass the correct encoding.

Upvotes: 2

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